In PlastiCity, four cities from the Interreg 2 Seas region join forces to develop new strategies and solutions to increase the recyclability of lost plastics.
PlastiCity invests in each city of the project in a number of innovative solutions for collection, characterisation and pre-processing of plastic business waste.
The first zone of the container comprises of a shredding and drying compartment. The size reduction of the collected plastic waste is a crucial step for further characterization, pre-treatment and processing steps. This is done with a shredder which is suitable for shredding both rigid plastics and flexible film fractions. The dryer will be used after washing steps or to dry extruded material to ensure proper storage for further testing following ISO norms.
The second zone of container 1 is contains all equipment that need water connection. Pre-treatment procedures are important in the purification of plastic waste. The main pre-treatment step is the washing of the waste plastics. Under the influence of friction, organic residues, adhesives and other contaminants are removed. Fibres such as paper are also removed during this washing procedure. For this purpose, an industrial sized washing machine is installed in the container. Wastewater is collected in IBC containers.
The mixing of plastics during reprocessing usually leads to reduced mechanical properties of these polymer blends. Polymeric contaminants are removed using separation techniques. A simple sink-float separation step can divide the light polyolefins (L(L)DPE, HDPE and PP) from the heavier (and often more polar) plastics PET, PA, PS, PVC, … This settling can be accelerated by using a centrifugal decanter. Here, the separation is performed under the influence of high g-forces. The centrifugal decanter is currently undergoing a maintenance step that is heavily delayed due to the corona-rules in place and is therefore currently not placed in the mobile unit but on the campus Kortrijk, where the maintenance is taking place.
Finally, the purified plastics must be dried before these can be processed and can for this purpose easily be transferred into the available dryers in the container.
This container is divided in the extrusion area and the lab/desk compartment.
In the extrusion area collected waste plastics can be reprocessed after leaving the pre-treatment container.
Re-melting can be realised by means of different processing techniques: injection moulding, extrusion, heat pressing, …
Extrusion is the most commonly used and again converts the plastic into uniform granules, therefore it was decided to include a state-of-the-art extruder (Labtech LE25-30/CV) with an accompanying cooling bath, calander and pelletizer in the mobile unit. During extrusion, the quality of the regranulate can be increased by degassing.
The use of a melt filter can remove the last remains of higher melting polymers or non-melting contaminants such as wood and rubbers. Both techniques can be used in the mobile unit.
The desk/lab compartment was planned to house the delicate analytical equipment for characterization of plastic waste and polymeric properties. As the mobile unit will not travel at the moment due to the regulations of the global corona pandemic, most of the analytic equipment (e.g., Balances, FTIR, DSC, TGA, Tensile tester Tinus Olsen, Pulverisette, MFI) are placed for safety reasons in the laboratories of Ghent University.